1. Field of the Invention
The present invention relates to a flow actuated valve for use in a wellbore. More particularly, the invention relates to a flow-actuated valve that is initially retained in an open position and is closeable with the application of fluid flow. More particularly still, the invention relates to a flow-actuated valve for use in float equipment to facilitate the injection of zonal isolation fluids into an annular area between a string of casing and a surrounding formation.
2. Description of the Related Art
Hydrocarbon wells are conventionally formed one section at a time. Typically, a first section of wellbore is drilled in the earth to a predetermined depth. Thereafter, that section is lined with a tubular string, or casing, to prevent cave-in. After the first section of the well is completed, another section of well is drilled and subsequently lined with its own string of tubulars, comprised of casing or liners. Each time a section of wellbore is completed and a section of tubulars is installed in the wellbore, the tubular is typically anchored into the wellbore through the use of wellbore zonal isolation fluids, i.e. cementing. Wellbore zonal isolation fluids includes, but not limited to, the injection of cement into an annular area formed between the exterior of the tubular string and the borehole in the earth therearound. Zonal isolation protects the integrity of the wellbore and is especially useful to prevent migration of hydrocarbons towards the surface of the well via the annulus.
Zonal Isolation of strings of tubulars in a wellbore is well-known in the art. Typically, the zonal isolation fluid is initially inserted in the tubular, and then forced to the bottom of the well and up the annular area toward the surface. With the use of other fluids, a column of zonal isolation fluids can be forced down the tubular string and into the annulus, resulting in a completely isolated annulus and leaving only a small amount of zonal isolation fluid at the bottom of the borehole. The cured fluid is drillable and is easily destroyed by subsequent drilling to form the next section of wellbore.
Float shoes and float collars facilitate zonal isolation procedures. In this specification, a float shoe is a valve-containing apparatus disposed at or near the lower end of the tubular string that is run into in a wellbore. A float collar is a valve-containing apparatus which is installed at some predetermined location, typically above a shoe within the tubular string. In certain cases, float collars are required rather than float shoes. However, in this specification, the term float shoe and float collar will be used interchangeably.
The main purpose of a float shoe is to facilitate the passage of zonal isolation fluids from the tubular to the annulus of the well while preventing the zonal isolation fluids from returning or xe2x80x9cu-tubingxe2x80x9d back into the tubular due to gravity and fluid density of the liquid zonal isolation fluids. In its most basic form, the float shoe includes a one way valve permitting fluid to flow in one direction through the valve, but preventing fluid from flowing back into the tubular from the opposite direction. The float shoes usually include a cone-shaped body to prevent binding of the tubular string during run-in.
As mentioned, wellbores are typically full of fluid to protect the drilled formation of the borehole and aid in carrying out cuttings created by a drill bit. When a new string of tubulars is inserted into the wellbore the tubulars must necessarily be filled with fluid to avoid buoyancy and equalize pressures between the inside and the outside of the tubular. For these reasons, a float shoe can be capable to temporarily permit fluid to flow inwards from the well bore as the tubular string is run into the wellbore and fills the tubular string with fluid. In one simple example, a spring loaded, normally closed, one-way valve in a float shoe is temporarily propped in an open position during run-in of the tubular by a wooden object which is thereafter destroyed and no longer affects the operation of the valve.
Other, more sophisticated solutions have been used that temporarily hold the valve in an open position and subsequently permit it to close and operate as a normally closed, one way valve. In a prior art arrangement, a valve is temporarily held in an open position during run-in and, thereafter, a weighted ball is dropped from the surface. The ball sinks to a seated position within the valve of a float collar and then, with pressure applied from the surface of the well, the valve is then enabled to shift to its normally closed position. In another prior art solution, a spring-loaded plunger is moved from an open position to a closed position utilizing hydrostatic pressure. The design utilizes an atmospheric chamber and shears screws. The number of shear screws determines the trip point of the device. As the tubular string is run deeper into a wellbore, hydrostatic pressure builds until it generates sufficient force on the shear screws to cause them to fail. The shearing action releases the plunger converting the valve to a normally closed, one-way valve.
More recently, spring loaded plunger valves in float shoes have been moved from a retained open position with the flow of fluid. The existing designs use energy from wellbore fluid that is circulated with pumps through the valve to depress the plunger and subsequently trip the device. These devices are typically comprised of some form of stop which temporarily retains the valve in an open position. Typically, wedges, tabs, balls, or knobs are mechanically lodged between the plunger and its retainer. These hold the plunger open against the spring force. When sufficient flow is established, the plunger moves downward, compressing the spring further and releasing the wedged stops.
There are problems associated with the prior art devices. Particularly, these devices are susceptible to premature release of the mechanism retaining the valve in an open position. For example, devices requiring a burst of fluid flow for de-activation can sometimes operate prematurely due to naturally occurring flow increases. Devices using an atmospheric chamber sometimes fail to operate as designed due to either design flaws or changes in well bore fluid density. If the valve releases premature, it is no longer possible to fill the tubular string with fluid from below. Because the tubular string must necessarily be filled with fluid to prevent pressure collapse and buoyancy, fluid must then be introduced from the surface of the well, thereby increasing the already high cost of completing drilled sections of wells.
The present invention generally relates to a flow-actuated valve for use in a wellbore. The invention includes a body having a closing member and a seat. The closing member and seat are separable to open and close the valve, thereby allowing the flow of fluid through the valve. The invention further includes a retainer to initially retain the valve in the open position absent a predetermined fluid flow rate in one direction for a predetermined time period. A biasing member thereafter urges the valve to the closed position, absent another fluid flow rate in one direction.
So that the manner in which the above recited features of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
FIG. 1 is a perspective view of a valve of the present invention.
FIG. 2 is an exploded view of the valve of FIG. 1.
FIG. 3 is a section view of the valve of FIG. 1, with a retention assembly retaining the valve in an open position.
FIG. 4 is a section view of a wellbore with a valve of the present invention disposed in a tubular.
FIG. 5 is a section view of the valve of FIG. 4 as the retention assembly is being deactivated.
FIG. 6 is a section view of the valve operable as a one way, normally closed valve.
FIG. 7 is a section view of the valve operating to permit fluid to flow from its upper end to and through its lower end.
FIG. 8 is a section view showing an alternative embodiment of the valve with a retention assembly activated.
FIG. 9 is a section view of the valve of FIG. 8 with the retention assembly deactivated.